Is the threat of Iran getting a nuclear weapon so great that Israel should contemplate military action? And should the US encourage it in that? These aren’t questions that Binyamin Netanyahu, the Prime Minister, appears to have answered for himself, for all his preoccupation with them. Nor does President Obama.

It’s a wretched dilemma, set to get worse as Iran’s nuclear programme advances, and the regime gets closer to having enough enriched uranium to make a warhead — even as it continues to deny that aim. Israel cares more about the threat than any other country, even its Arab neighbours, feeling itself uniquely at risk. Yet short of military action — and probably not even that — there is no action that Israel can take on its own that really tackles that overwhelming anxiety.

“I am an Israeli. I will not depend on anybody for my existence,” said one senior government adviser yesterday, speaking for many of his countrymen. “I will not rely on American guarantees, and I will do whatever I need to defend myself, and the hell with it,” he said.

A dependence on the US for every solution to the Iranian threat has led Israeli leaders into an increasingly shrill petition, tugging at the sleeve of George W. Bush, and now Obama, for reassurance that they take the threat seriously, before retreating for a brief while, inevitably unsatisfied. In his pitch to Obama, misjudged on a dozen counts, Netanyahu made a link — which some US officials found absurd — between what concessions Israel might make on the Palestinian front and what it wants the US to do on Iran. On the Palestinian conflict, Obama officials have reminded Israel, it has few allies; on Iran, it has the support of the US, Europe, and now its Arab neighbours.

But Netanyahu’s non sequitur makes sense as a coded request for a package of things Israel wants the US to do. First are more sanctions, a call that the Obama team may now consider more actively, given the Iranian regime’s crackdown on election dissent.

The chances for Obama’s strategy of engagement now look poor; the value of adding a few threats to his offer may be rising. Israeli lobbyists in Washington want Obama to target Iran’s imports of petrol and exports of oil, the weak points in its economy — and for the US to do it alone if Europe won’t join in.

In theory, some senior Israeli advisers say, they would like the US at least to be prepared to mount its own military action against Iran. But it is unrealistic to expect Obama, after making his speech to the Muslim world in Cairo, finally extracting US troops from the setbacks of Iraq and, now, wanting to encourage young Iranians who want to displace their President, to attack Iran to prevent it getting a bomb.

Would Israel strike on its own? There is a tortuous debate on this issue among those who make these calculations for a living — and the conclusion tends to be a “no”.

There are technical barriers: Israel’s aircraft would have to fly over Iraq, and refuel as well. Just possibly, they could avoid that with extension fuel tanks, but intelligence reports say that the US has refused to sell those to Israel. Even if Israel overcame these barriers and tried to strike without US permission, the world would assume it had been given a tacit go-ahead, which could take the US into a regional war. It would be a reckless Israeli leader that reckoned the Iranian threat was worth the risk of shattering the US relationship.

No Israeli minister would ever take the possibility of strikes off the table. But every way you cut it, strikes look like a horrible option, even for those who feel that an Iranian bomb is intolerable.

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